I'd say look up BGP (Border Gateeway Protocol,) but the wiki page buries the important parts, since it describes the protocol state machine and packet format be

I'd say look up BGP (Border Gateeway Protocol,) but the wiki page buries the important parts, since it describes the protocol state machine and packet format before even attempting to give a high level picture. AS, standing for Autonomous System, is like an ISP's name. BGP spreads routing information by rumor. For example, I start the rumor that I can route to IP addresses in 1.2.3.0/24, and tell my peer ISPs. They tell their peers I told them... etc. To prevent rumors from going in circles, you keep a record of every ISP in the path of spreading the rumor, and call it the AS path. (Otherwise you could never retract the rumor, as it would go in circles. BGP speakers do not accept rumors that they themselves are in the path of. (Except in cases of dirty hacks, but then only a finite number of times.)) This article describes fraudulent AS paths attached to (as I understood it) IP ranges that were legitimately owned by the people advertising them to Hurricane Electric. This is like you telling Hurricane Electric that I (the North Korean ISP) told you that I can route to 1.2.3.0/24, an IP address range you own, even though I told you no such thing and we are not even peers.